Katrina forms

Slow-to-organize TD 12 (now Katrina) continues to look better on satellite imagery, with deep convection on the east side continuing to build. The upper level outflow has improved considerably today, and there does not appear to be any major shearing of the system happening. Water vapor imagery does show some dry air to the northwest of the storm, and this dry air is currently the main obstacle that has slowed Katrina's development this morning. The latest Hurricane Hunter report at 7:30am EDT found a not-too-impressive central pressure of 1007 mb, but a respectable 45 knots of wind at flight level (1500 feet). The Hurricane Hunters noted some low-level banding beginning to occur, and it is a very safe bet that this system will continue to intensify today.

The track of the storm will take it over Florida by Friday, all the computer models agree. The exact landfall point is unclear, since the depression is moving slowly and erratically, and may undergo a reorganization where the center relocates under the main area of convection later today. The models forecast a landfall intensity anywhere from 35 mph winds to 70 mph winds. The higher range is possible if the convection on the east side manages to overcome the dry air on the west side and wrap all the way around the system by Thursday morning. Let's call it a 30% chance Katrina will be a Category 1 hurricane by landfall on Friday.

Once over Florida, the GFS model forecasts that the system will stall and not move for several days. All of the other models disagree, and push the system into the Gulf of Mexico by Sunday, where it has an excellent chance of intensifying into a hurricane. Since the GFS it the only model calling for this stall, it is more believable to assume that Katrina will push into the Gulf of Mexico and threaten the U.S. Gulf coast early next week.

Dr. Jeff Masters